To determine the value of epidermal growth factor receptor (EGFR) gene amplification as a biological prognostic indicator in patients with esophageal squamous cell carcinoma, the EGFR gene amplification was determined by slot-blot hybridization using DNA extracted from formalin-fixed and paraffin-embedded blocks of tissues from 107 patients with esophageal squamous cell carcinoma who had undergone curative surgery. Results were analyzed by both univariate and multivariate statistical analysis. EGFR gene amplification greater than 3-fold was detected in the primary tumors of 13 (12%) of the 107 cases. The cumulative survival rate for patients with EGFR gene amplification in the primary tumors was significantly lower than that for patients without amplification (P < 0.001). A significant correlation was observed between extensive lymph node involvement at the time of surgery and EGFR gene amplification (P < 0.05). In the multivariate analysis, EGFR gene amplification (P = 0.015) and vascular invasion (P = 0.003) proved to retain independent prognostic values. These results suggest that EGFR gene amplification may be a useful biological marker for the prediction of lymph node metastasis and a poorer prognosis of esophageal squamous cell carcinoma.